1861950091 has 2 divisors, whose sum is σ = 1861950092. Its totient is φ = 1861950090.

The previous prime is 1861950089. The next prime is 1861950127. The reversal of 1861950091 is 1900591681.

It is a weak prime.

It is an emirp because it is prime and its reverse (1900591681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1861950091 - 2¹ = 1861950089 is a prime.

Together with 1861950089, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1861957091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 930975045 + 930975046.

It is an arithmetic number, because the mean of its divisors is an integer number (930975046).

Almost surely, 2^1861950091 is an apocalyptic number.

1861950091 is a deficient number, since it is larger than the sum of its proper divisors (1).

1861950091 is an equidigital number, since it uses as much as digits as its factorization.

1861950091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 40.

The square root of 1861950091 is about 43150.3197091285. The cubic root of 1861950091 is about 1230.2385883481.

The spelling of 1861950091 in words is "one billion, eight hundred sixty-one million, nine hundred fifty thousand, ninety-one".